Breast cancer is a significant health problem in both developed and developing countries. It is estimated that each year the disease is diagnosed in over 1,000,000 women worldwide and is the cause of death in over 400,000 women. There are many treatment options available, including surgery, chemotherapy, radiation therapy, and hormonal therapy. These treatments are significantly more effective in reducing the mortality of the disease with early detection through breast cancer screening programmes.
The standard method for detection of breast cancer is mammography. However mammography can cause significant patient discomfort and requires radiation exposure. Furthermore there are often variable results and inconsistencies in reading and interpreting the images of breast tissue from the X-Ray machine especially for smaller tumour sizes of the order of 1-5 mm.
Digital Image based Elasto-tomography is an emerging technology for non-invasive breast cancer screening without the requirement of radiation. As used herein, Digital Image-based Elasto-Tomography system will be referred to as a DIET system. The DIET system uses digital imaging of an actuated breast surface to determine tissue surface motion. It then reconstructs the three-dimensional internal tissue stiffness distribution from that motion. Regions of high stiffness suggest cancer since cancerous tissue is between 3 and 10 times stiffer than healthy tissue in the breast. This approach eliminates the need for X-Rays and excessive, potentially painful compression of the breast as required in a mammogram. Hence, screening could start much younger and enjoy greater compliance. Presently, there are other elasto-tomographic methods based on magnetic resonance and ultrasound modalities. Both methods are capable of measuring the tissue elasticity and they are undergoing rapid development across the globe. However, they are also costly, in terms of equipment, and take significant time to use. They are therefore limited for practical screening applications.
The DIET system, in contrast, is silicon based and is thus potentially low cost and portable, so the technology could be used in any medical centre, particularly in remote areas. In addition, the use of silicon technology ensures that as it improves and scales upward in capability so will the DIET system performance. This scalability of performance is not true for X-Ray or ultrasound based approaches.
The DIET system relies on a fast and accurate measurement of the actuated breast using multiple calibrated high-resolution digital cameras. Furthermore small perturbations and variations on the surface must be measured accurately to ensure smaller tumours are not missed. Therefore, there exists a need in the art for very high-resolution feature registration and motion tracking system that can deal with the unique requirements of a DIET system. In addition, for clinical effectiveness, the measured motion must be done with a minimal amount computation.